Bomb threats are cheap and effective ways to disrupt a civilized society. Schools, museums, business districts, government buildings, and sporting events can all be thrown into chaos with a single phone call. We might be seeing a whole lot more of this in the future.
Civilization is an intricate lattice of cultural artifacts and beliefs and accepted behaviors. It’s easier to tear civilization apart than it is to build one up.
Bomb threats were a thing back in the early 70’s. They just sort of fizzled out. And that was before calls could be traced easily. Now you need to use a burner phone, and even that can be traced, geographically.